Thermoplastic polyurethane copolymer molding compositions

ABSTRACT

Compositions for forming molded articles, particularly, shells for automotive applications are made up of melt blends of an aliphatic thermoplastic urethane elastomer and one or more polyolefin-based modifiers. These compositions may be blended to form a powder, pellets, microspheres or minibeads which may then be cast to form air bag door and instrument panel cover skins which may meet automotive deployment and weathering requirements.

FIELD OF THE INVENTION

This invention relates to compositions which are blends of (a)thermoplastic polyurethanes and (b) at least one copolymer and/or alloy.These blends are suitable for molding, particularly suitable for slushmolding to form a shell having improved feel. The shell also maintainsgood weathering and air bag deployment properties.

BACKGROUND OF THE INVENTION

The use of low unsaturation level polyols made from double metal cyanidecatalysts in combination with chain extenders in the preparation ofthermoplastic elastomers is known. Compositions made with such polyolsare disclosed, for example, in U.S. Pat. Nos. 5,096,993 and 5,185,420.

Prior to the use of double metal cyanide catalysts for the preparationof high molecular weight polyols, the thermoplastic polyurethaneelastomers produced with polyoxyalkylene polyols had poor physicalproperties, such as being too hard, due to high levels of terminalunsaturation in the polyols used in their production. The thermoplasticpolyurethane elastomers disclosed in U.S. Pat. Nos. 5,096,993 and5,185,420 are thermoplastic elastomers made with polyols having lessthan 0.04 meq/g of end group unsaturation. These thermoplasticelastomers are taught to have enhanced softness.

Because of their softness, thermoplastic elastomers are frequently usedin the construction of automotive interior trim components. Automotivemanufacturers frequently specify that the elastomers used to produceinterior trim components must have adequate long-term stability andresistance to degradation by ultraviolet light and that the elastomersmust also meet specific manufacturing specifications for resistance toultraviolet light exposure, particularly in the case of instrumentpanels.

In order to achieve manufacturing specifications for resistance toultraviolet exposure, antioxidants, ultraviolet light stabilizingagent(s) and pigment(s) may be added to elastomers.

Additionally, due to the presence of end group unsaturation ofpreviously available polyols with molecular weights greater than 2,000,soft (low durometer) aliphatic thermoplastic urethane elastomers havenot been available in a dry castable powder particle forms.

U.S. Pat. Nos. 5,824,738 and 6,187,859 disclose aliphatic urethaneelastomer compositions comprising low end group unsaturation, lowmolecular weight polyols stabilized with one or more ultravioletstabilizing agents, an antioxidant and pigments. While the performanceof such elastomers has been outstanding, the relatively high cost ofthese elastomers due to their use of aliphatic isocyanates has limitedtheir commercial desirability.

One approach taken to reduce the cost of these aliphatic urethaneelastomer compositions is to blend the aliphatic thermoplasticpolyurethane with a less expensive polymeric material. However, suchblends tend to separate under production conditions. Such separationadversely affects the physical properties of the final product.

U.S. Pat. No. 4,883,837 discloses one technique for producing compatibleblends of polyolefins with thermoplastic polyurethanes. In the blendsdisclosed in U.S. Pat. No. 4,883,837, a modified polyolefin is alsoincluded in the blended composition. The blends taught in U.S. Pat. No.4,883,837 are made up of from 15 to 60 wt. % of polyolefin, from 30 to70 wt. % thermoplastic polyurethane and from 10 to 35 wt. % modifiedpolyolefin. It is the modified polyolefin which acts a compatibilizingagent for the polyolefin and thermoplastic polyurethane.

U.S. Pat. No. 5,109,050 discloses a composition made up of from 80-99parts by weight of a thermoplastic polyurethane resin and from 1 to 20parts by weight of a modified polyolefin resin. Any of the knownthermoplastic polyurethane resins may be used in the compositions ofU.S. Pat. No. 5,109,050. Any of the known modified polyolefin resins maybe used in the compositions of U.S. Pat. No. 5,109,050. The compositionsdescribed in U.S. Pat. No. 5,109,050 are taught to be flexible, smoothto the touch and stretchable. It is these properties which are said tomake these compositions particularly useful for producing diapers.

U.S. Pat. No. 5,852,118 discloses block copolymers of chemicallymodified polyolefins with thermoplastic polyurethanes, copolyesters orcopolyamides and a coupling agent. The coupling agent is a diisocyanatewith blocked or unblocked polyisocyanates. This diisocyanate couplingagent may be used in combination with a co-coupling agent selected fromprimary amines, secondary amines, diols, diepoxides, amino/hydroxy andamino/epoxy compounds. These block copolymers are useful ascompatibilizing blends of polar and non-polar thermoplastic elastomersand for promoting adhesion of thermoplastic elastomers onto variouspolar engineering resins.

U.S. Pat. No. 5,605,961 discloses homogeneous thermoplastic compositionswhich include (1) a polyolefin selected from isotactic polypropylene,syndiotactic polypropylene and a blend of isotactic polypropylene andthermoplastic polyurethane and (2) a mixture of from 1 to 99%thermoplastic polyurethane and from 1 to 99% of the reaction product ofa modified polyolefin and a polyamide resin.

U.S. Pat. No. 5,623,019 discloses a compatibilized thermoplastic moldingcomposition made up of from 30 to 90% thermoplastic polyurethane, 10 to70% of a polyolefin having a number average molecular weight of at least10,000 and a compatibilizing agent which is a copolymer having a numberaverage molecular weight of from 25,000 to 350,000 and containing blocksof monoalkylene arene and either hydrogenated conjugated diene ornon-hydrogenated conjugated diene.

U.S. Pat. No. 6,054,533 discloses compatibilized blends of athermoplastic elastomer and a polyolefin in which the compatibilizingagent is a thermoplastic polyurethane. This thermoplastic polyurethanecompatibilizing agent is the reaction product of a substantiallyhydrocarbon intermediate, a diisocyanate and an amine or diol chainextender. The thermoplastic polyurethane compatibilizing agent isincluded in an amount of from 0.25 to 15 parts by weight for every 100parts by weight of thermoplastic elastomer plus polyolefin.

U.S. Pat. No. 6,174,959 discloses compatible blends of from 50 to 99% ofan aliphatic thermoplastic polyurethane with from 1 to 50% of acopolymer composed of units derived from ethylene and propylene with25-35% by weight of the copolymer being derived from propylene units.The polyether polyols used to produce the thermoplastic polyurethanesrequired in U.S. Pat. No. 6,174,959 may have functionalities no greaterthan 6 and molecular weights of from 400 up to 20,000. There is noteaching in this disclosure with respect to the unsaturation level ofthe polyether polyols used to produce the thermoplastic polyurethanesused in these blends.

U.S. Pat. No. 6,235,830 discloses a polyurethane resin for slush moldingcomposed of a thermoplastic polyurethane elastomer, a plasticizer and acompound containing a radical polymerizable unsaturated group. Theplasticizer is included in an amount of from 5 to 50 parts by weight per100 parts by weight of polyurethane elastomer. The compound containing aradical polymerizable unsaturated group is included in an amount of from0.1 to 10 parts by weight per 100 parts by weight of polyurethaneelastomer.

-   -   U.S. Pat. No. 6,365,674 discloses thermoplastic polyurethane        resins which form compatible blends with polyolefins. The        compatibility described therein is taught to be attributable to        production of the thermoplastic polyurethane from a reaction        mixture which includes a reactive polyolefin containing at least        one hydroxyl, amine or carboxylic acid functional group.

U.S. Pat. No. 6,414,081 discloses compatibilized blends of non-polarthermoplastic elastomers and polar thermoplastic polymers such asthermoplastic polyurethanes in which from 1 to 40 parts by weight, basedon 100 parts by weight of blend, is a compatibilizer. Suitablecompatibilizers include: (1) the condensation reaction product of 10-90wt. % of functionalized polymer with 10-90 wt. % of polyamide or (2) ablend of 10-90 wt. % functionalized polymer with 10-90 wt. % polyamideor (3) a mixture of (1) and (2).

U.S. Pat. No. 6,469,099 and EP 1,235,879 B1 each disclose compatibilizedresin blends which include a thermoplastic polyurethane, asuccinimide-based compatibilizing agent containing pendantisocyanate-reactive groups or polyoxyalkylene groups corresponding to aspecified structure. The compatibilizing agent is used in amountsranging from 0.5 wt. % to 20 wt. %, depending upon the particularapplication for which the product resin will be used.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a thermoplasticpolyurethane composition having a tensile strength less than 2800 psiwhich is more economical than commercially available aliphatic urethaneelastomers but which can still be molded, preferably slush molded, toproduce elastomers having properties comparable to those of currentlyavailable aliphatic urethane elastomers.

It is also an object of the present invention to provide a compatibleblend of thermoplastic polyurethane and at least one copolymer and/oralloy without the need for an added compatibilizing agent.

These and other objects which will be apparent to those skilled in theart are accomplished with the compatible blend of (1) a polyolefin-basedmodifier characterized by a repeating —CH_(2—)structure and (2) analiphatic thermoplastic polyurethane composition which has been producedfrom a high molecular weight polyether polyol (Molecular weight=1000 to10000 Da) with an unsaturation level less than or equal to 0.04 meq/g. Akey feature of this compatible blend is that no external compatibilizingagent is added to the blend.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention provides a moldable composition, preferably aslush moldable composition, which is composed of a compatible blend offrom 5 to 95 wt. %, based on total weight of moldable composition,preferably, from 45 to 90 wt. % of a light stable polyether polyol-basedaliphatic thermoplastic urethane (TPU) elastomer and from 5 to 95 wt. %,based on total weight of moldable composition, preferably, from 5 to 45wt. % of a modifier which is a block copolymer and/or elastomer alloycharacterized by a repeating —CH₂— structure. Preferred modifiers arethermoplastic vulcanizates and block copolymers based on styrene andethylene and/or butylene. Particularly preferred compositions furtherinclude up to 10% by weight, preferably, up to 5% by weight, mostpreferably, up to 2% by weight, of an ionomer.

The thermoplastic polyurethane elastomer may be the reaction product of(a) a relatively low unsaturation, low molecular weight polyol, (b) oneor more chain extenders, (c) an aliphatic diisocyanate and (d) aurethane catalyst, and optionally, (e) an ultraviolet stabilizing agent,(f) an antioxidant and/or (g) pigment.

The thermoplastic polyurethane blends of the present invention producedwith an olefin-containing block copolymer and/or thermoplastic alloy arecharacterized by an ability to maintain low temperature resistance(ductility to about −30° C.) and also weatherability (DE<3.0 after 1993kilojoules/m²). Olefin-containing block copolymers and/or alloys havinga Tg value of about −90° C. are particularly desirable for use in thepractice of the present invention. The olefin-containing blockcopolymers and/or alloys used as modifiers in the present inventioninclude those copolymers containing a —CH₂-type repeating unit structurehaving substituted alkylene functionality(ies), and blends of suchcopolymers. The number average molecular weight of the polyalkyleneblock copolymer and/or alloy modifiers employed in the present inventionwill generally be less than or equal to about 100,000, including allvalues and increments therein. Particularly preferred olefin-containingblock copolymers may also be further characterized by their rheology.For example, these preferred polyolefin modifiers may be such that ashear viscosity of about 900 (MPa) at a shear rate of 250 sec drops to ashear viscosity of about 150 (MPa) at about 2100 sec.

In another embodiment of the present invention, the olefin-containingelastomer alloy may include a thermoplastic vulcanizate (TPV), such as avulcanized terpolymer of ethylene/propylene/diene dispersed throughout acontinuous matrix of thermoplastic material. Vulcanizate or vulcanizedas used herein means that the dispersed terpolymer has some level ofcrosslinking but the alloy still possesses the ability to be meltblended and/or melt processed.

Other copolymers which are suitable for use as the modifier in thecompositions of the present invention include block copolymers based onstyrene and ethylene/butylene, including linear triblock copolymers.These may be hydrogenated styrene-ethylene-butylene-styrene (S-EB-S) orstyrene-ethylene-propylene-styrene (S-EP-S), or they may have styrenecopolymerized in the midblock (S-(EB/S)-S) or they may be unsaturatedwith styrene copolymerized in the midblock as in non-hydrogenatedstyrene-isoprene/butadiene-styrene copolymers (S-I/B-S).

The elastomer alloys used as modifiers in the present invention includeelastomers containing a —CH₂-type repeating unit structure havingsubstituted alkylene functionality(ies) and some degree of crosslinking.Blends of such alloys may be used. The number average molecular weightof the elastomer alloy modifiers employed in the present invention willgenerally be less than or equal to about 100,000, including all valuesand increments therein. Particularly preferred elastomer alloys may alsobe further characterized by their rheology. For example, these preferredelastomer alloy modifiers may be such that a shear viscosity of about900 (MPa) at a shear rate of 250 sec drops to a shear viscosity of about150 (MPa) at about 2100 sec.

A portion of the olefin-containing block copolymer and/or elastomeralloy may be replaced with an ionomer, such as the ethylene methacrylicacid copolymers in which part of the methacrylic acid is neutralizedwith a metal ion such as zinc or sodium, which is commercially availablefrom DuPont under the name Surlyn®. Such an ionomer reduces surfaceporosity and improves weathering when higher levels of the polyolefinare used. The composition may be melt compounded and formed intopellets, powder, microspheres or minibeads for slush casting of skins orshells for automotive interior panels, particularly instrument panels.

As noted above, thermoplastic polyurethane alloy compositions within thescope of the present invention are capable of meeting automotiveweathering requirements, for instance, exposure to 1993 kilojoules/m² ofXenon arc artificial weathering with a delta E (color change) less thanor equal to 3. Instrument panel skins molded from these thermoplasticpolyurethane alloy compositions are expected to be capable ofwithstanding successful air bag deployments at −30° C. and 107° C. andafter heat aging for 400 hours at 107° C.

One measurement which is used for predicting fragmentation of a coverskin for an air bag during deployment is the retention of elongationafter heat aging after 500 hours at 120° C. As will be seen in theExamples of this application, the thermoplastic polyurethane alloycompositions of the present invention do retain sufficient elongationafter heat aging under these conditions (preferably, 100% or higher,most preferably, 150% or higher) to indicate that these compositions arecapable of withstanding successful air bag deployments.

The present invention also provides a method for preparing light stableautomotive components from a polyether polyol-based aliphatic urethanethermoplastic elastomer melt-blended with an olefin-containing blockcopolymer, and a method for preparing such a composition into slushcastable powder, pellets, microspheres or minibeads. The compositionalso may be used as the outer layer of a double cast skin.

Additionally, the present invention provides a skin, cover or shell,particularly for automotive trim panels, and more particularly for airbag door and instrument panel applications, which are produced from themelt-blended composition of a light stable polyether polyol-basedaliphatic thermoplastic urethane elastomer and an olefin-containingblock copolymer of the present invention.

Aliphatic thermoplastic urethane (TPU) elastomers which are suitable foruse in the alloy compositions of the present invention are known tothose skilled in the art. Examples of suitable TPU elastomers aredisclosed in U.S. Pat. Nos. 5,824,738 and 6,187,859. Suitable aliphaticurethane elastomer compositions may be produced from low end groupunsaturation, low molecular weight polyols which are reacted with analiphatic diisocyanate and stabilized with one or more ultravioletstabilizing agents, an antioxidant and pigments.

It has been found that compositions within the scope of the presentinvention may be produced by melt blending one or more olefin-containingblock copolymers with one or more aliphatic thermoplastic elastomers atweight ratios wherein the amount of olefin-containing block copolymer isequal to or less than the amount of aliphatic TPU. Alloy compositionsmade at these ratios have been found to be capable of meeting automotiveair bag cover weathering and deployment requirements.

In another embodiment of the present invention, substitution of about5-10% of the olefin-containing block copolymer with an ionomer has beenfound to provide improved weathering and less surface porosity,particularly when higher amounts of modifier are present.

The alloy compositions of the present invention may be prepared by meltblending the aliphatic TPU elastomer with the olefin-containing blockcopolymer (with or without ionomer) using a twin screw extruder. Pelletsmay then be formed and cryogenically ground to form a slush castablepowder. The output of the extruder may also be formed into minibeads ormicrospheres according to the teachings of U.S. Pat. Nos. 5,525,274;5,525,284; 5,564,102; 5,998,030; 6,410,141 and 6,632,525.

The TPU used in the present invention may be the reaction product of oneor more low unsaturation (i.e., unsaturation level of less than 0.04meq/g, preferably less than 0.02 meq/g) polyether polyol, one or morechain extenders and an aliphatic organic diisocyanate.

As used herein, an aliphatic diisocyanate is a diisocyanate thatcontains only hydrocarbon functionality such as hexamethylenediisocyanate or (HMDI). The overall level of aliphatic functionality ofa diisocyanate may therefore be greater than 75% (wt.) and fall withinthe range of 75-100% (wt).

A completely (100% wt.) aliphatic polyurethane is a polyurethaneproduced from one or more aliphatic diisocyanates, one or more aliphaticpolyols (e.g., aliphatic, polyether or polyester) and one or morealiphatic chain extenders. The aliphatic polyurethane so prepared mayalso be prepared in the presence of a urethane catalyst.

The weight percent ratio of TPU in the TPU alloy composition of thepresent invention may be from 5-95% by weight (based on total weight ofTPU plus polyolefin modifier) and the weight percent of the polyolefinmodifier may be from 5 to 95% by weight (based on total weight of TPUplus olefin), including all values and increments therein. In apreferred embodiment of the present invention, the TPU may be present inan amount of 50% by weight (based on total weight of TPU plus olefinmodifier) and the polyolefin modifier may also be present at about 50%by weight (based on total weight of TPU plus olefin modifier). In aparticularly preferred embodiment of the present invention, 45-90% byweight TPU and 5-45% by weight olefin modifier are present.

As used herein, a terpolymer is a polymer having three differentrepeating units which may be present in block, random or evenalternating configuration. These repeating units may be polyalkylenetype repeating units (e.g. —CH2-) which may be substituted withadditional hydrocarbon functionality.

In another embodiment of the present invention, the olefin-containingblock copolymer may be a vulcanized terpolymer ofethylene/propylene/diene dispersed in polypropylene or polyethylene,such as that which is commercially available under the trademarkSantoprene™ 8211-55B100 from Advanced Elastomer Systems. Thesevulcanized terpolymers generally have a specific gravity of about 1.04,a tensile strength at break (ASTM D412) of about 590 psi, an elongationat break (ASTM D412) of about 600%, and a compression set (257° F., 70.0hr) of about 55% (ASTM D395).

Suitable thermoplastic vulcanizates are those that have relatively lowlevels of crosslinking and/or an elongation at break of between100-1000%, including all values and increments therein.

In another embodiment of the present invention, the block copolymer forblending with the light-stable TPU may be any of the styrenic blockcopolymers with a hydrogenated midblock ofstyrene-ethylene/butylene-styrene (SEBS) or styreneethylene/propylene-styrene (SEPS). Such styrenic block copolymersinclude that which is commercially available under the designationKraton G from Kraton Polymers Group. Olefin-containing block copolymerscomposed of a linear triblock copolymer based on styrene andethylene/butylenes, such as those which are commercially available underthe designations MD 6945M and G1643M, from the Kraton Polymers Group arealso suitable modifiers for the compositions of the present invention.

Block copolymers of SBS (styrene butadiene-styrene) and SIS(styrene-isoprene-styrene) may also be used to produce the alloycompositions of the present invention.

The olefin-containing block copolymers used in the practice of thepresent invention may also be one or more of thermoplastic elastomers(TPE), such as that which is commercially available under thedesignation Tekron® from Teknor Apex.

Thermoplastic vulcanizates (TPV) such as those which are available fromTeknor Apex Company under the trademarks Uniprene®; Telecar®(thermoplastic rubbers (TPR)), Monprene® (TPO/saturated styrene blockcopolymers), and Elexar® SEBS are also suitable for use in the presentinvention.

Olefin-containing block copolymers such as those composed of a blockcopolymer thermoplastic elastomer which are available from Teknor Apexunder the designations TK-1448A and TK-1468D are also suitable for usein the present invention.

The olefin containing block copolymer which is an ethylene-octenecopolymer that is commercially available under the name Engage™8400Polyolefin Elastomer from Dow Plastics is also suitable for use in thepresent invention.

The TPU/olefin-containing copolymer compositions of the presentinvention may also contain fillers, pigments or other additives whichmay function to improve processing and/or product performance. Suchadditives may be present at levels which may be up to about 15% byweight in total.

For higher ratios of certain copolymers, e.g., when the olefinicmodifier is used in an amount above about 30%, it has been found that insome cases, the addition of an ionomer, such as Surlyn® 9970 or Surlyn®9975, may improve weatherability of the TPU alloy and reduce surfaceporosity. Surlyn® 9970 is an advanced ethylene/methacrylic acidcopolymer in which the methacrylic acid groups have been partiallyneutralized with zinc ions which is commercially available from DuPont.

The melt blend of TPU/olefin-containing block copolymer (with or withoutionomer) may also include a color concentrate as a source of color.Suitable color concentrates are known to those skilled in the art. Oneexample of a suitable color concentrate is that which is commerciallyavailable under the name Clariant 374A Pebble from Clariant Corporation.This product may include about 30% by weight pigment(s), about 5-10% ofan antioxidant (e.g., Tinuvin 213 from Ciba-Geigy) and about 60-65% ofan aliphatic TPU suitable for use in the composition of the presentinvention. The color concentrate may be present in an amount of fromabout 5 to about 10% by weight of the TPU alloy.

Typical compositions which may be melt blended to form the slushcastable elastomers of the present invention include:

-   -   a) 45-90% by weight, based on total weight of melt blend,        aliphatic TPU (produced with a polyol having an unsaturation        level less than 0.04 meq/g);    -   b) 5-45% by weight, based on total weight of melt blend, of        olefin-containing block copolymer modifier;    -   c) up to 30% by weight, based on total weight of melt blend, of        ionomer (preferably, Surlyn® 9970 or 9975 ionomer);    -   d) 0-10% by weight, based on total weight of melt blend, of        color concentrate (preferably, Clariant 374A color concentrate),        in place of a portion of the olefin-containing block biopolymer        modifier.

The slush castable elastomers formed from the melt blending of the aboveingredients will generally have a melt flow index (MR) of about 38(grams/10 minutes, 160° C./10 kilograms). The compatible blends of thepresent invention will generally have MFI's of between 20-150, includingall values and increments herein.

The thermoplastic polyurethanes employed to produce the compatibleblends of the present invention may be made by a “one-shot” reactionprocess. The “one-shot” technique involves mixing, in a suitablecontainer, polyol, chain extender, organic diisocyanate, any ultravioletstabilizing agent(s), any antioxidant, any pigment(s) or colorconcentrate, and urethane catalyst and, then, agitating the mixture forapproximately 20 to 30 seconds. These thermoplastic polyurethanes canalso be made by pre-blending a portion of the polyol, any antioxidant,catalyst and any UV/heat stabilizers. The polyol blend may be added toan agitated, heated tank of a urethane casting machine: isocyanate isplaced into a separate agitated, heated tank; chain extender/crosslinkeris placed into a third tank; and pigment masterbatch with the additionalpolyol is added at the mixhead. The components are metered individuallyusing gear pumps or other pumps with the required metering accuracy,with suitable flow control devices, to a low pressure mixhead forblending. This mixture may be cast onto a temperature and speedcontrolled belt for completion of the reaction. Various temperaturescould be maintained in different areas of the chamber.

The mixture from the mixing head of the urethane casting machine mayalso be used as the feed for a twin screw extruder. Various screwsections can be set up to convey the liquid to continue polymerization,melt and blend the elastomers and the final unpigmented elastomer couldbe fed to a strand the for pelletizing. The extruder output could alsobe used to make beads of the desired size for dry casting.

The extrusion operation could also be used to melt blend dry pigment forcoloring/pigmenting the elastomers. The dry blended pigment would be fedinto the extruder using a side feeder which would meter the properamount into a clear melt mixture. The output of the side feeder would besynchronized with the output of the extruder.

The ingredients may also be fed directly into the throat of the twinscrew extruder which would perform the blending, polymerization,melting, and pigmentation operations.

In preparing the improved light stable polyether/polyol based aliphaticurethane thermoplastic elastomer used to produce the compositions of thepresent invention, the polyether/polyol, diisocyanate, chain extender,and other components are typically reacted under conditions of elevatedtemperature. A preferred method of forming the desired thermoplasticelastomers is by continuous processing utilizing an extruder. Analternative method involves mixing in a “one shot” batch process, thepolyol, chain extender, organic diisocyanate, ultra violet stabilizingagent, antioxidant, pigment, and urethane catalyst in a vessel toproduce the elastomer of the present invention.

this aliphatic thermoplastic polyurethane elastomer is then combinedwith the polyolefin-based modifier in the appropriate amount by any ofthe techniques known to those skilled in the art.

The mixture of aliphatic thermoplastic polyurethane and polyolefin-basedmodifier is then placed into a suitable container where it is heatedand, then, the mixture is chopped or ground into a powder using either anon-cryogenic or a cryogenic methods such as liquid nitrogen tofacilitate and expedite the granularization or pelletizing of the slushmolding composition.

One method for producing a powder or particle is described in U.S. Pat.No. 5,525,274. In this method, spherical particles having a diameterbetween 0.007 and 0.040 inches are formed by melt extruding the mixtureof thermoplastic polyurethane and any other additives, particularly, apigment and then directing the molten material through orifices withopenings of the desired size into a liquid bath. The molten materialpassing into the liquid bath is cut into pieces to cause that moltenmaterial to be shaped into microspheres. This same process is suitablefor the aliphatic thermoplastic polyurethane plus polyolefin-basedmodifier mixture from which the slush molding compositions of thepresent invention are formed. The powder or beads obtained are suitablefor use as a castable powder. That is, the powder can be placed in amolding tool and heated to form an article of manufacture. Non-cryogenicgrinding is made possible by changing the index of the aliphaticthermoplastic polyurethane elastomer. The index is the ratio of reactiveequivalents of NCO containing components/reactive equivalents of OH andNH containing components. This change reduces the molecular weight ofthe elastomer and its inherent toughness allowing the polymer to beground at ambient temperatures. The polymer may be prepared at an NCO/OHequivalent ratio of from 0.90 to 0.99 with a preferred range of 0.94 to0.98.

The mixing of the polyurethane-forming reactants can be carried out atambient temperature (approximately 25° C.) and the resulting mixture isthen heated to a temperature of the order of about 40 to about 130° C.,preferably to a temperature of about 90 to 120° C.

While any of the known aliphatic diisocyanates may be used to producethe thermoplastic polyurethanes of the present invention, diisocyanateswhich are particularly useful include: isophorone diisocyanate,hexamethylene diisocyanate, methylene bis(cyclohexyl isocyanate), itsisomers and mixtures thereof, isomers and isomeric mixtures ofcyclohexylene diisocyanate, 1-methyl-2,5-cyclohexylene diisocyanate,1-methyl-2,4-cyclohexylene diisocyanate, 1-methyl-2,6-cyclohexylenediisocyanate, 4,4′-isopropylidene bis(cyclohexyl isocyanate) andmixtures and derivatives thereof. The organic diisocyanates can bepresent in amounts ranging from 20% to 50% but are preferably present inamounts in the range of approximately 25% to 40%.

Preferred polyol reactants for producing the aliphatic thermoplasticpolyurethanes used in the present invention are polyether polyols andcombinations thereof. Suitable polyols include at least one etherstructural unit and have a number average molecular weight of from 1000to 10,000 Da, preferably, at least 1250 and most preferably, at least2,000 but less than 10,000 Da, preferably, less than 8,000 Da. Thefunctionality of the polyol is preferably from 2 to 4. Suitablepolyether polyols include polyoxyethylene glycols, polyoxypropyleneglycols, copolymers of ethylene oxide and propylene oxide,polytetramethylene glycols, and copolymers of tetrahydrofuran andethylene oxide and/or propylene oxide. It is, of course, possible to usesuch polyether polyols in combination with other known polyols (e.g.,polyester polyols) but such other types of polyols should not be used inan amount greater than 50%. Preferably the polyether polyol is of thetype produced using an organometallic catalyst which results in a polyolhaving a level of terminal unsaturation of less than 0.04 meq/g, andpreferably less than 0.02 meq/g. A representative example of such apolyol is Acclaim 4220N (sold by Bayer MaterialScience LLC). Acclaim4220N polyol is an ethylene oxide capped poly(propylene oxide) polyolwith an approximate molecular weight of 4000 and a hydroxyl number of28. The polyol component can be present in amounts ranging fromapproximately 40% to 70%. The preferred concentration of polyol presentin the reaction ranges between 40% and 60% and is adjusted in this rangeto vary the hardness of the elastomer produced.

Chain extending agents which may be employed in the preparation of theurethane thermoplastic elastomer used in the present invention includediols and aromatic secondary or aliphatic primary or secondary diamines,all of which are well known in the art.

Preferred diol chain extenders include ethylene glycol, diethyleneglycol, propylene glycol, pentane diol, 3-methylpentane-1,5-diol,1,6-hexane diol, HQEE [hydroquinone bis(2-hydroxyethyl)ether], CHDM(1,4-cyclohexanedimethanol), HBPA (hydrogenated bisphenol A), 1,4-butanediol, neopentyl glycol, and dipropylene glycol can also be used.

In a particularly preferred embodiment, the chain extender is1,4-butanediol. The chain extender, such as 1,4-butanediol, can bepresent in concentrations varying from 6% to 15%, but preferably rangesfrom 7% to approximately 13%.

The ultraviolet stabilizing agents include a combination of a hinderedamine light stabilizers (HALS) such asbis(1,2,2,6,6-pentamethyl-1-4-piperidinyl) sebacate (Chemical AbstractNumber 41556-26-7, also known as Tinuvin 292 or 765 Ciba-Geigy Corp.,Hawthorne, N.Y.) and a hydroxyphenyl benzotriazole such as abenzotriazole mixture of poly(oxy-1,2-ethanediyl),alpha-[3-[3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropyl]-omega-hydroxy-and poly(oxy-1,2-ethanediyl),alpha-[3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropyl)-omega-[3-[(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropoxy)-,Chemical Abstract Number 104810-47-1 and polyethylene glycol with amolecular weight of 300 Chemical Abstract Number 25322-68-3 (also knownas Tinuvin 1130 or 213 Ciba-Geigy Corp., Hawthorne, N.Y.) and any othersuitable ultraviolet stabilizing agents. The combination of ultravioletstabilizing agents being present in a ratio in a range of approximately1:1 to 2:1, with 2:1 being the preferred ratio, at a total concentrationin the range of approximately 0.5 to 2.0%, with 2.0% being the preferredconcentration.

Any suitable antioxidant, or mixture of antioxidants, may be used in theelastomer forming process of the present invention. Representativeexamples include Irganox 1010[tetrakis(methylene(3,5-di-tert-butyl-4-hydroxycinnamate)]methane fromCiba-Geigy; Irganox 1076 [Ortodecyl 3,5di-tert-butyl-4-hydroxyhydrocinnamate] from Ciba-Geigy; Irganox 245[Ethylenebis(oxyethylene)bis-(3-tert-butyl-4-hydroxy-5-methylhydrocinnamate)] from Ciba-Geigy;and Vanox 830 (a proprietary blend of a phenolic compound, alkylateddiphenylamines and trialkyl phosphite from R. T. Vanderbilt). Theantioxidants may be present at a total concentration in a range ofapproximately 0.10% to 1.0%, but are preferably present in the range ofapproximately 0.25% to 0.75%.

Any suitable pigmenting agent or mixture of pigmenting agents may beused to produce the compositions of the present invention. The agent oragents must have long-term ultraviolet light resistance for Arizonaexposure; heat resistance up to 260° C. (500° F.) to survive the drycasting process, and the extrusion compounding process; and must notpromote any degradation of the urethane elastomer. Representativepigments include carbon black (Columbian Chemicals Corporation; titaniumdioxide (DuPont Company, Chemicals Department); Chomophthal Red BPP(Ciba-Geigy, Pigments Division); Phthalocyanine Blue Red Shade(Ciba-Geigy, Pigments Divisions); Yellow iron Oxide (Miles Incorporated,Organic Products Division); and Quinacridone Violet (Hoechst CelaneseCorporation, Specialty Products Group-Pigments). The pigmenting agentbeing present at a total concentration in the range of approximately0.90% to 2.0% and preferably in a range wherein the total concentrationis approximately 1.0% to 1.94%.

The urethane catalysts which are useful in the present invention may beany suitable urethane catalyst, or mixture of urethane catalyst, may beused in the elastomer forming process of the present invention.Representative samples include (a) tertiary amines such as ZF-20 [bis2-(N,N-dimethylamino)ether] from Huntsman Chemical; N-methylmorpholinefrom Huntsman Chemical; N-ethylmorpholine from Huntsman Chemical; DMEAN,N-dimethylethanolamine from Union Carbide; Dabco1,4-diazbioyclo[2,2,2]octane from Air Products and the like; (b) saltsof organic acids with a variety of metals such as alkali metals,alkaline earth metals, Al, Sn, Pb, Mn, Co, Ni, and Cu, including, forexample, sodium acetate, potassium laurate, calcium hexanoate, stannousacetate, and stannous octoate, and the like; (c) organometallicderivatives of tetravalent tin, trivalent and pentavalent As, Sb, andBi, and metal carbonyls of iron and cobalt. Useful organotin compoundsinclude dialkyltin salts of carboxylic acids, e.g., dibutyltindiacetate, dibutyltin dilaurate, dibutyltin maleate, dilauryltindiacetate, dioctyltin diacetate and the like. Preferred catalysts areBiCat 8, BiCat 12, BiCat V and Coscat 83. The BiCat materials areproducts of Shepherd Chemical. Coscat 83 is a product of CasChem.Corporation. BiCats 8 and 12 are mixtures of bismuth and zinccarboxylates. BiCat V and Coscat 83 are bismuth neodecanoates. Thesecatalysts are present at a total concentration in the range ofapproximately of 0.1% to 0.3% by weight, and preferably in the range ofapproximately 0.15% to 0.25%.

This aliphatic thermoplastic polyurethane elastomer is then combinedwith the polyolefin-based modifier in the appropriate amount by any ofthe techniques known to those skilled in the art.

The mixture of aliphatic thermoplastic polyurethane and polyolefin-basedmodifier may, for example, be placed into a suitable container and thenchopped or ground into a powder using either a non-cryogenic or acryogenic methods such as liquid nitrogen to facilitate and expedite thegranularization or pelletizing of the slush molding composition.

One method for producing a powder or particle is described in U.S. Pat.No. 5,525,274. In this method, spherical particles having a diameterbetween 0.007 and 0.040 inches are formed by melt extruding the mixtureof thermoplastic polyurethane and any other additives, particularly, apigment and then directing the molten material through orifices withopenings of the desired size into a liquid bath. The molten materialpassing into the liquid bath is cut into pieces to cause that moltenmaterial to be shaped into microspheres. This process is suitable forprocessing the aliphatic thermoplastic polyurethane pluspolyolefin-based modifier mixture from which the slush moldingcompositions of the present invention are formed. The resulting powderor beads are then suitable for use as a castable powder. This powder canbe placed in a molding tool and heated to form an article ofmanufacture.

Automobile interior trim components having increased ultraviolet lightstability and resistance to artificial weathering can be produced bycontinuous processing utilizing an extruder wherein the virgin elastomeris extruded and molded into automotive interior trim components as iswell known in the art in the alternative, the castable powder elastomer,described above, may be added to a mold and heated to produce anautomotive trim component.

In accordance with another aspect of the invention, the slush moldingcomposition of the present invention in the form of a powder ormicrospheres may be used to produce articles by roto-casting. In suchprocess, a predetermined charge of materials is placed within a hollowmold that is supported on an arm of a centrifuge. The centrifuge has amotor that will drive the arm to cause the charge of material to flowevenly across the inner surface of the mold. The mold is heated to causethe slush molding composition to melt as it flows evenly across theinner surface of the mold to build-up a uniform thickness shell on themold. The mold and shell are cooled and the mold is opened to remove theshell as a finished part or a near net shape part for final finishing.

In accordance with another aspect of the invention, the slush moldingcomposition of the present invention in the form of a powder ormicrospheres (particularly, microspheres in the size range of 0.007″ to0.040″) is suitable for use in slush molding. In such a process, anexcess charge of the slush molding composition is placed in a charge orpowder box. The box is connected to a mold having a cavity formed inpart by a casting surface heated or cooled by a suitable heater or aircooling system. Once the box is connected to the mold, the box and moldare inverted so that the excess charge of materials is dumped into themold cavity. Typical slush molding apparatus are described in U.S. Pat.Nos. 4,722,678; 4,878,827 and 4,056,941. The apparatus described inthese patents maintain a static head of material over the layer ofmaterial that is dumped onto the casting surface of the mold cavity. Theheating system provides heated air (other suitable heaters are suitablefor use with the invention such as the hot oil heater of U.S. Pat. No.4,389,177 or electrical heaters as shown in U.S. Pat. No. 4,979,888).The casting surface is heated to cause the thermoplastic melt extrudedmicrospheres to melt as they are flowed evenly across the castingsurface and compacted thereon by the static head of the overlyingmaterial. It has been found that this enables a wider range ofmicrosphere sizes to be used for build-up of a uniform thickness shellon the casting surface having low porosity that is below a visualthreshold for holes in the skin.

The mold cavity is cooled by suitable air cooling or liquid coolingsystems as shown in U.S. Pat. Nos. 4,621,994; 4,623,503 and 5,106,285.The shell is concurrently cooled and the powder box and mold cavity areseparated so that the mold is opened to remove the well as a finishedpart or a near net shape part, for final finishing.

The slush molding compositions of the present invention can be used tocast shells. Minibeads and spheroidal particles made by extruding themixture of aliphatic thermoplastic polyurethane, polyolefin-basedmodifier and any other additives and pelletizing this mixture with anunderwater pelletizing system, have been successfully cast into shellsusing the same equipment as used for powder. The low-melt viscosity ofthe composition of the present invention contributes greatly to thesuccess in using this material to cast shells. The benefits seen areimproved flow into areas with small radii and return edges, easier cleanup and loading, and increased bulk density of the particle.

Pigmented slush molding compositions can be produced from the aliphaticthermoplastic urethane elastomer (TPU) plus polyolefin-based modifierusing a single or twin screw extruder. Twin screw extruders can also beused to make thermoplastic urethane elastomers which are non-pigmented.These materials are then pigmented in a second operation by using colorconcentrates for injection molding or dry/wet pigments in a secondextruder or other high-intensity mixers for other applications. Aftermelting the elastomer, the dry (heat and UV stable automotive grade)pigments and other additives (antioxidants, release agents etc.) couldbe metered into the melt stream of the reactor to produce the desiredcolor and then the melt could be fed to the pelletizing unit to producepellets that can be further dried for use. This process reduces thehandling operations currently used to pigment elastomers. The heathistory that the materials would experience lowers cost and provides amore uniform product pellets for the casting process.

In practice, a thin shell, having a thickness between about 0.5 and 1.5mm, may be formed by first providing a mold with a mold surfaceconfigured to complement the desired shape of the shell to be molded.The mold surface may then be heated (via suitable heaters such as a hotoil heater, or an electrical heater, or hot air or infrared heating).The heated casting surface may then cause the melt extruded microspheres(particles, pellets, etc.) of the inventive composition to melt as theyare flowed evenly across the casting surface and compacted thereon bythe static head of the overlying material. It has been found that thisenables a wider range of particle sizes to be used for build-up of ashell having a uniform thickness on the casting surface and low porositythat may be below a visual threshold for holes in the skin.

The compositions of the present invention may also comprise the outerlayer of a dual layer cast shell in which the composition of the presentinvention is applied as an outer layer, and a second layer which maycomprise a different material, e.g., an aromatic based polyurethanecomposition. The layers may be of about equal thickness. That is, theinner layer of the skin or shell of the dual layer cast shell may beprimarily aromatic based. An aromatic polyurethane type inner layershould be understood herein to be a polyurethane produced from anaromatic diisocyanate and/or the use of an aromatic diisocyanate alongwith an aromatic extender. However, in either case, such aromaticpolyurethane may utilize a polyol, including an aliphatic polyol (e.g.,aliphatic polyether or aliphatic polyester). Accordingly, it can beappreciated that the use of an aromatic diisocyanate or even an aromaticextender may serve to increase a physical property such as heatresistance. The aromatic based inner layer may therefore be one that hasa DE>3.0 after 1993 kiloJoules/m² of Xenon arc exposure. The aromaticpolyurethane so prepared may also be prepared in the presence of aurethane catalyst.

The aromatic urethane composition, also preferably in the form of a dryparticulate, such as powder or microspheres, may be cast on the innersurface of the outer layer formed of the first aliphatic urethanematerial. The aromatic urethane material may be al/owed to melt and forman inner layer at least partially, and preferably completely, coveringthe inner surface of the outer layer. Sufficient heat may be transferredfrom the heated mold surface through the outer layer to melt the innerlayer. The mold surface may then be cooled or allowed to cool which mayallow the inner and outer layers to harden and bond together. Finally,the shell is removed from the mold.

It is further contemplated that the inner layer of the dual layer castshell may comprise regrind or recycled plastic. In one exemplaryembodiment, the inner layer may comprise a polymer material, a portionof which comprised a formed article prior to its use as the polymermaterial for the inner layer. By formed article, it is meant to includepolymer material that has, e.g., experienced a prior plasticsmanufacturing operation, such as slush molding or injection molding,wherein the plastic material has been converted, by heat, or by heat andpressure, into some desired shape, but which may not have survived aquality control measure, and may have been rejected by the manufacturerfor commercial release. This would also include materials recovered inmanufacture such as trim scrap and faulty parts (regrind or recycle),and materials recovered from discarded post-consumer products (reclaim).

Having thus described the invention, the following Examples are given asbeing illustrative thereof.

EXAMPLES

The following materials were used in these Examples:

-   TPU A: Reaction product of:    -   1) 100 parts by weight of a polyol component made up of:        -   a) 81.6 parts by weight of the polyether polyol having a            functionality of 2 and a molecular weight of 4000 with an            unsaturation level of less than 0.04 meq/g (commercially            available under the name Acclaim 4220N from Bayer            MaterialScience),        -   b) 12.8 parts by weight of butanediol,        -   c) 2.02 parts by weight of hindered amine light stabilizer            (Hastavin 3055),        -   d) 0.99 parts by weight of a substituted benzotriazole            mixture which is commercially available under the name            Tinuvin 213 from Ciba Geigy,        -   e) 1.5 parts by weight of the proprietary release agent            designated Techlube 721-SP-1 which is commercially available            from Technick,        -   f) 0.75 parts by weight of the silicone surfactant which is            commercially available under the name Silwet L-2622 from            OSI, and        -   g) 0.58 parts by weight of bismuth neodecanoate            with    -   2) 41.62 parts by weight of the liquid cycloaliphatic        diisocyanate having an NCO content of 31.8% minimum which is        commercially available under the name Desmodur W from Bayer        MaterialScience.-   TPU B: Reaction product of:    -   1) 100 parts by weight of a polyol component made up of:        -   a) 51.18 parts by weight of the polyether polyol having a            functionality of 2 and a molecular weight of 4000 with an            unsaturation level of less than 0.04 meq/g (commercially            available under the name Acclaim 4220N from Bayer            MaterialScience),        -   b) 9.15 parts by weight of butanediol,        -   c) 1.63 parts by weight of hindered amine light stabilizer            (Hastovin 3055),        -   d) 0.71 parts by weight of a substituted benzotriazole            mixture which is commercially available under the name            Tinuvin 213 from Ciba Geigy, and        -   e) 0.2 parts by weight of the catalyst Coscat 83 which is            commercially available from Vertellus Specialties Inc.            with    -   2) 30.30 parts by weight of the liquid cycloaliphatic        diisocyanate having an NCO content of 31.8% minimum which is        commercially available under the name Desmodur W from Bayer        MaterialScience,-   MODIFIER A: A mixture of crosslinked EPDM rubber in polypropylene    which is commercially available under the name Santoprene    8211-55B100 from ExxonMobil Chemical.-   MODIFIER B: A block copolymer of polystyrene and polybutadiene which    is commercially available under the name Kraton MD6945M from Kraton    Polymers.-   MODIFIER C: A block copolymer of polystyrene and polybutadiene which    is commercially available under the name Kraton G1643M from Kraton    Polymers.-   MODIFIER D: A block copolymer of polystyrene and polybutadiene which    is commercially available under the name Kraton FG 1901X-1000 from    Kraton Polymers,-   MODIFIER E: A block copolymer having a repeating —CH₂— structure    which is commercially available under the designation Tekron    TK-1468A from Teknor Apex.-   MODIFIER F: A block copolymer having a repeating —CH₂— structure    which is commercially available under the designation Tekron    TK-1468D from Teknor Apex.-   MODIFIER G: A thermoplastic vulcanizate which is commercially    available from ExxonMobil under the name Santoprene 291-75B150.-   COLORANT A: Clariant 374A Pebble.-   COLORANT B: Clariant 2N4A Medium Dark Flint-   IONOMER A: An ethylene methacrylic acid copolymer in which part of    the methacrylic acid is neutralized with a metal ion which is    commercially available under the name Surlyn 9770 from E.I. DuPont    de Nemours.

Examples 1-11

TPU A or TPU B, at least one of the above-described MODIFIERS andoptionally IONOMER A or COLORANT A or COLORANT B were melt blended inthe amounts indicated in the Tables which follow in a twin screwextruder, such a 27 mm. Leistritz. The extruder was set up to have zonetemperatures between 155 and 165° C. with the screw operating at 300 rpmfeeding a 3 hole pelletizer die. Microspheres in the size range of about0.007″ to about 0.040″ were formed from the extruder described above inthe manner described in U.S. Pat. Nos. 5,525,274 and 5,525,284. Thesemicrospheres were suitable for use in slush molding. These microspheresof the inventive composition may be cast to form skins or shells.

In these Examples, the TPU/olefin-containing block copolymer meltblended extrudate was cryogenically ground to form a powder for slushcasting.

Exemplary formulations of the present invention which, may be suitableas the slush cast skin capable of meeting automotive weathering anddeployment requirements, in addition to an automotive material testingspecification, such as Ford WSS-M15P45A are shown below in Tables 1-3.

TABLE 1 Example 1 2 TPU A (pbw) 66.5 76.5 MODIFIER A (pbw) 30 20COLORANT A (pbw) 3.5 3.5 Tensile Strength 560 745 Initial Elongation (%)200 304 Elongation after Heat 102 120 Aging (%) Delta E after 1993 kJ/m²1.967 1.626 pbw = pails by weight

Because weathering resistance according to SAE J1885 (1993 kiloJoule/m²Xenon Arc exposure) of 3.0 or less is generally acceptable for U.S.automotive air bag doors and instrument panels, the formulations ofExamples 1 and 2 would be expected to be suitable for use in automotiveair bags and instrument panels.

TABLE 2 Example 3 4 5 6 7 TPU A (pbw) 75.5 74.5 62.5 76.5 76.5 MODIFIERB 20 20 0 20 0 (pbw) MODIFIER C 0 0 30 0 20 (pbw) MODIFIER D 1 4 4 0 0(pbw) COLORANT 3.5 3.5 3.5 3.5 3.5 A (pbw) Tensile — 731 — 731 —Strength Initial 250 255 — 255 — Elongation (%) Elongation 189 157 — 160— after Heat Aging (%) pbw = parts by weight

TABLE 3 Example 8 9 10 11 TPU A (pbw) 73 63 73 63 MODFIER E 20 30 0 0(pbw) MODIFIER F 0 0 20 30 (pbw) COLORANT A 7 7 7 7 (pbw) Tensile — — —— Strength pbw = parts by weiqht

Example 12

76.5 parts by weight of TPU B, 20.0 parts by weight of MODIFIER G, and3.5 parts by weight of COLORANT B were melt blended in a twin screwextruder. The extruder was set up to have zone temperatures between 155and 165° C. with the screw operating at 300 rpm feeding a 3 holepelletizer die. Microspheres in the size range of about 0.007″ about0.040″ were formed from the extruder described above in the mannerdescribed in U.S. Pat. Nos. 5,525,274 and 5,525,284. These microsphereswere suitable for use in slush molding. These microspheres of theinventive composition may be cast to form skins or shells.

While not being bound by any particular theory, it is believed that thepresent disclosure illustrates an unexpected degree of compatibilitybetween constituents that, in the past, have been considered generallyincompatible, due to somewhat miscible domains formed in the specificthermoplastic urethane composition used. This unexpected compatibilityis believed to be the result of using an aliphatic diisocyanate incombination with an extender (e.g., 1,4-butanediol) which may then becoupled to polyols with a low mount of unsaturation (i.e., unsaturationlevels below 0.04 meq/g). Thus low unsaturation-type polyol may providea domain capable of compatible blending with the olefin-containing blockcopolymers described herein, when melt blended with the thermoplasticurethane.

The inventive compositions disclosed herein may be formed into the skinsor shells of the present invention by any of the known processes formaking such articles, including cast molding, slush molding, injectionmolding, blow molding, transfer molding, rotational molding andinjection-compression molding.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology which has been used is intended to bein the nature of words of description rather than of limitation.Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that the invention may be practiced otherwise than asspecifically described.

Although the invention has been described in detail in the foregoing forthe purpose of illustration, it is to be understood that such detail issolely for that purpose and that variations can be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention, except as it may be limited by the claims.

What is claimed is:
 1. A molding composition consisting of a compatibleblend of a) from 5 to 95 wt. % of an aliphatic thermoplasticpolyurethane comprising the reaction product of (i) a polyol componentcomprising at least one polyether polyol having a molecular weight offrom 1000 to 10,000 Da and an unsaturation level less than or equal to0.04 meq/g, (ii) an isocyanate component comprising at least onealiphatic organic diisocyanate, (iii) a chain extender, (iv) optionally,a UV stabilizing agent, (v) optionally, an antioxidant, (vi) optionally,a pigment, and (vii) a catalyst which promotes urethane formation, b)from 5 to 95 wt. % of a polyolefin-based modifier selected from thegroup consisting of a vulcanized terpolymer of ethylene/propylene/dienedispersed in polypropylene, a vulcanized terpolymer ofethylene/propylene/diene dispersed in polyethylene, a styrenic blockcopolymer with a hydrogenated midblock ofstyrene-ethylene/butylene-styrene (SEBS), a styrenic block copolymerwith a hydrogenated midblock of styrene ethylene/propylene-styrene(SEPS), a block copolymer of styrene butadiene-styrene (SBS), a blockcopolymer of styrene-isoprene-styrene (SIS), and an ethylene-octenecopolymer, c) optionally, a UV stabilizing agent, d) optionally, anantioxidant, e) optionally, a pigment, f) optionally, a mold releaseagent, and g) optionally, an ethylene/methacrylic acid copolymer inwhich the methacrylic acid groups have been partially neutralized. 2.The composition of claim 1 in which the modifier b) has a shearviscosity of approximately 900 at a shear rate of 250 sec⁻¹ which dropsto approximately 150 at 2100 sec⁻¹.
 3. The composition of claim 1 inwhich the polyther polyol in a)(i) has an unsaturation level of lessthan 0.02 meq/g.
 4. The composition of claim 1 in which the aliphaticdiisocyanate is selected from the group consisting of hexamethylenediisocyanate, hydrogenated diphenylmethane diisocyanate, and isophoronediisocyanate.
 5. The composition of claim 1 in which the chain extenderis selected from the group consisting of ethylene glycol, diethyleneglycol, propylene glycol, 1,4-butane diol, pentane diol,3-methylpentane-1,5-diol, 1,6-hexane diol, hydroquinonebis(2-hydroxyethyl) ether, 1,4-cyclohexanedimethanol, neopentyl glycol,and hydrogenated bisphenol A.
 6. The composition of claim 1 in which aportion of the ethylene/methacrylic acid copolymer is neutralized with ametal ion.
 7. The composition of claim 1 in which modifier b) is avulcanized terpolymer of ethylene, propylene, and diene dispersed in apolyolefin.
 8. The composition of claim 1 in which a) is produced from amixture comprising from 40 to 70 wt. %, based on total weight of thethermoplastic composition, of the polyol component.
 9. The compositionof claim 1 in which a) and b), and optionally, c), d), e) f), or g) aremelt blended.
 10. The composition of claim 1 comprising: a) 45-90 wt. %of aliphatic thermoplastic polyurethane; b) 5-45 wt. % ofpolyolefin-based modifier; and e) 5-10 wt. % color concentrate, with thetotal amount of a), b) and e) being equal to 100 wt. %.
 11. Thecomposition of claim 1 comprising: a) 45-90 wt. % of aliphaticthermoplastic polyurethane; b) 5-45 wt. % of polyolefin-based modifierand up to 10 wt. % ionomer; and e) 5-10 wt. % color concentrate, withthe total amount of a), b) and e) being equal to 100 wt. %.
 12. Thecomposition of claim 1 in which the ratio of a) to b) by weight isgreater than or equal to 1:1.
 13. The composition of claim 1 in whichthe modifier b) is selected from linear triblock copolymers of styrene,ethylene, and butylene, hydrogenated styrene-ethylene-butylene-styrene,hydrogenated styrene-ethylene-propylene-styrene, styrene copolymerizedin midblock, or unsaturated styrene copolymerized in midblock.
 14. Athermoplastic polyurethane produced from only the composition of claim1, characterized by a DE less than or equal to 3 after exposure to 1993kiloJoules/m² of Xenon arc.
 15. A thermoplastic polyurethane producedfrom only the composition of claim 1, characterized by elongation atbreak after heat aging of at least 100% after 500 hours at 120° C.
 16. Athermoplastic polyurethane produced from only the composition of claim1, characterized by elongation at break before heat aging of from 300 to600%.
 17. A slush castable powder, pellet, microsphere, or minibeadconsisting of the composition of claim
 1. 18. A thermoformed sheetproduced from only the composition of claim
 1. 19. A process forproducing a slush castable powder comprising cryogenically grinding amelt blended extrudate comprising the composition of claim
 1. 20. Aprocess for producing slush castable microspheres comprising meltblending the composition of claim 1 in an extruder, passing the meltblended composition through a die, and cutting the composition exitingthe die.
 21. A process for producing slush castable powder comprisingunderwater grinding of a melt blended extrudate comprising thecomposition of claim
 1. 22. A process for the production of a singlelayer cast shell, comprising: a) applying only the composition of claim1 to a mold surface; b) heating the mold surface to cause the appliedcomposition to melt; c) allowing the melt to flow over the mold surface;and d) allowing the melt to cool.
 23. A molded article produced by theprocess of claim
 22. 24. A process for the production of a dual layercoast shell, comprising: a) applying only the composition of claim 1 toa mold as an outer layer; b) applying an inner layer comprising anothercomposition to the outer layer; and c) molding the inner and outerlayers in a manner such that the inner and outer layers harden and bondtogether.
 25. The process of claim 24 in which the inner layercomposition is a polyurethane produced from an aromatic polyisocyanate.26. The process of claim 24 in which the inner layer composition has amelt flow comparable to that of the composition of claim 1 used as theouter layer.
 27. A molded article produced by the process of claim 26.28. A molded article in the form of a skin, cover or shell produced bythe process of claim
 26. 29. A process for the production of an article,comprising injection molding only the composition of claim
 1. 30. Aninjection molded article produced by the process of claim 29.